Apparatus for automatically developing printing plates

ABSTRACT

An apparatus for the automatic developing of printing plates wherein at least two distributing rollers are positioned above a conveyor belt adapted to carry the printing plates to be processed, with each roller being mounted for rotation in a direction opposite to the direction of travel of the conveyor belt and being axially slidable transversely of the belt thereby to apply the developer uniformly to the surface of the plates in a manner similar to prior manual methods.

United States Patent 72] Inventor Ewald Puls Altenrather Str. 30, D 521Troisdorf, Germany [21] Appl. No. 776,995

[22] Filed Nov. 19, 1968 [45] Patented Dec. 7, 1971 [32] Priority May28, 1968 [33] Germany [31] Pl7725l2.l

[54] APPARATUS FOR AUTOMATICALLY DEVELOPING PRINTING PLATES 14 Claims, 2Drawing Figs.

[52] U.S. Cl 95/89 R, 95/89 A, 118/242 [51] Int. Cl G03d 5/06 [50] Fieldof Search 95/89 R, 89 I A, 89 F, 93, 94 R;118/242 [56] References CitedUNITED STATES PATENTS 3,435,749 4/1969 Cauwe etal.

1,946,627 2/1934 Karrer.. 95/89 UX 2,154,585 4/1939 Samandji.. 95/89(FEED) 3,059,560 10/1962 Gutzmer 95/89 3,113,034 12/1963 Fix 118/242 XFOREIGN PATENTS 87,711 8/1959 Denmark .l 95/89 949,710 9/1956 Germany95/89 997,409 7/1965 Great Britain 95/94 Primary E.raminer-Samuel S.Matthews Assistant Examiner- Robert P. Greiner Anorney--Oberlin, Maky,Donnelly & Renner ABSTRACT: An apparatus for the automatic developing ofprinting plates wherein at least two distributing rollers are positionedabove a conveyor belt adapted to carry the printing plates to beprocessed, with each roller being mounted for rotation in a directionopposite to the direction of travel of the conveyor belt and beingaxially slidable transversely of the belt thereby to apply the developeruniformly to the surface of the plates in a manner similar to priormanual methods.

PATENTEUUEC mu 3.625.131

sum 1 or 2 FIG.1

YXXXXXXXXXXXX XX PATENIED DEC 7 Ian SHEET 2 OF 2 APPARATUS FORAUTOMATICALLY DEVELOPING PRINTING PLATES The present invention relatesto an apparatus for the automatic developing and rinsing of printingplates, particularly offset plates. The developing of printing plates isat present still carried out by hand since efforts to constructs amechanical device for developing the plates as uniformly and in the samequality as by hand have not yet met with success. To be sure, attemptsof developing ofiset plates mechanically have been made. In suchattempts the developer was applied to the exposed plates by rollers thatmoved slightly in a lateral direction and performed a rotary movement.However, in carrying out this developing process, the development wasnot uniform, and the rollers for distributing the developer left stripesbehind on the finished plates which reproduced the lateral movement ofthe rollers by a sinusoidal curve.

The rollers of these prior devices which failed in practice were notcapable of imitating the rotary movement, hitherto executed manually, ofthe cloth imbued with developer and thus were not able to apply thedeveloper to the plate uniformly and with a uniform action thereon.

An object of the present invention is to provide a mechanical apparatuscapable of imitating in a practically identical way by mechanicalmovements the manual efiort hitherto required for the developing ofprinting plates and particularly offset plates.

To accomplish this task, the present invention provides an apparatus ofthe aforementioned kind and which includes a developing tank and aconveyor belt which carries the plates to be processed. The developer isdistributed by at least two rollers positioned near the upper section ofthe belt, the rollers preferably rotating about their axes to the pathof travel of said belt and in opposite directions being slidable backand forth in an axial direction. A washing tank with conveyor rollersfor washing the completely developed printing plates is located adjacentthe developing tank. In the washing tank, the developer is removed fromthe plates by means of sprays of water or another suitable washingliquid.

All rollers are preferably provided with a common drive mechanism, anddevices for spraying the developer and the washing liquid are mounted inthe individual tanks.

To provide a special support for the printing plates to be processed,the lower section of the conveyor belt passes through a liquid bath,e.g., through the developer flowing down from the printing plates in thedeveloping tank. The upper surface of the conveyor belt is thereforealways moist so that the smooth back surfaces of the printing platesadhere sufficiently to the conveyor belt but are lifted off therefromwithout difficulty at the end of the developing tank prior to entry intothe washing tank.

It has been found that the rotary movement of the pieces of cloth or thelike used in the manual developing can be imitated in the best manner ifthe distributing rollers are driven in the direction opposite to thedirection in which the printing plates are processed, and move laterallythrough a range of between 50 to 100 mm. Such lateral movement ispreferably produced according to the present invention by a lever arm.The free end of the shaft mounting each distributing roller isoperatively engaged by such lever arm whose other end is pivotallyconnected to a crank driven by a separated motor. Due to the rotarymovement, in opposite directions, of the distributing rollers, thedeveloper can be retained on the upper surface of the printing plates inlarger quantities, e.g. in the form of an accumulation so that it actswith uniform intensity and for a sufficient period of time upon theindividual plates. The relatively large lateral movement of thedistributing rollers, in combination with the rotary movement inopposite directions simulates sufficiently the rotary movement requiredin manual operation.

The invention makes it possible to develop printing plates andparticularly offset plates automatically, manual operation being largelyavoided, in a quality indistinguishable from that obtained in manualdeveloping. Thus, the speed of developing of printing plates andparticularly offset plates can be substan tially increased.

In the accompanying drawings:

H6. 1 is a vertical cross-sectional view of the apparatus of the presentinvention, and

FIG. 2 is a sectional view taken along line 11-11 of FIG. 1.

Referring now in more detail to the drawing, wherein like parts areindicated by like reference numerals, a tank 2 for developing the offsetplates is mounted on frame 1. The plates are fed into the apparatus overtable 3 and leave the developing tank over table 4 which leads to awashing tank 5 fastened to a support 6 on the back of frame 1. Thedeveloping tank 2 consists of a detachable tub 7 and a hood 8 resting onlateral support pins 9.

The suction line 10 of pump 11 is connected to the drain outlet 7a ofthe tub 7. The pump 11 is driven by a drive mechanism (not shown) whichcirculates the developer in the form of bath 12 contained in tub 7 tospray devices to be presently described.

A conveyor belt 13 is mounted inside the developing tank 2, with theupper section of the belt lying in the same plane as tables 3 and 4,while the lower section of the belt 13 is immersed in bath 12. Theconveyor belt 13 passes over a driven, deflecting roller 14 and a freeroller 15, with the upper section of the conveyor belt 13 being held ina horizontal plane by support rollers 16 and 17.

Two rotatable distributing rollers 18 and 19 are mounted in thedeveloping tank 2 above the conveyor belt 13, with the rollers 18 and 19being driven in a direction opposite to that of the movement of conveyorbelt 13, as indicated by arrows 20 and 21. These distributing rollers 18and 19 are provided with a felt coat 22, and are arranged verticallydirectly above the support rollers 16 and 17 and can be made to restagainst these support rollers by means of adjusting handles 23 in amanner described below.

At the front and rear end of developing tank 2 press-on rollers 24 and25 are mounted above the upper section of conveyor belt 13 and are incontact therewith. The rollers 24 and 25 provide a full abutment of theprinting plates against the upper section of the conveyor belt 13 duringthe passage through developing tank 2.

In washing tank 5 are mounted two pairs of vertically aligned conveyorrollers 26 and 27 which abut against each other and which conduct thedeveloped printing plates through the washing tank. A device 28 forspraying washing water or the like is mounted between the rollers 26 and27, the device 28 spraying the processed printing plates from all sideswith washing liquid. The space between roller pairs 26 and 27 is sosmall that the printing plates are always seized and held by at leastone of these roller pairs. A pump 29 for circulating the washing liquidis connected with the spraying device 28 by tube 30. The completelydeveloped and rinsed printing plates leave washing tank 5 over table 31.

All driven rollers receive their rotary movement from a common drivemotor, not shown in the drawing. For this purpose a chain drive isprovided which is propelled by the drive motor and which passes overchain wheels coordinated with the individual rollers to be driven. FIG.2 shows only one of these chain wheels, namely chain wheel 32 which iscoordinated with one of the distributing rollers, namely 18. Rollerpairs 26 and 27 are driven at a reduced r.p.m. through a conventionalreduction gear (not shown).

As shown in FIG. 2, distributing rollers 18 and 19 are mounted on stubshafts 33 and 34 mounted on frame 1 in vertically adjustable supportblocks 35 and 36. These support blocks can be vertically adjusted bymeans of adjusting handles 23 and adjusting spindles 37 connectedthereto, whereby the spacing between the distributing rollers andconveyor belt 13 can be regulated. The support blocks are mounted so asto move vertically in lateral guides, e.g., in angle-shaped guide ribsor dovetail guides.

Bearing bushings 38 and 39 are mounted in support blocks 36 and 35,respectively, and rotate within roller bearings 40 and 41. The drivechain wheel 32 is mounted on the outer end of bushing 38.

Stub shafts 33 and 34 are arranged so as to be axially displaceable inbearing bushings 39 and 38, respectively, and are operatively connectedthereto by carriers 42 in such a manner as to be secured againstrotation. Thus, distributing rollers 18 and 19 can be moved laterallyback and forth above conveyor belt 13 in a manner described below, andare mounted for rotary movement about their longitudinal axes throughchain wheels 32.

The entire drive mechanism is lodged in a casing 43 mounted laterally onframe 1, while the support blocks are covered by a casing 44 at thefront side of the apparatus.

All support blocks of the distributing rollers are mounted in the guidesso as to be easily replaceable, whereby the cleaning of the apparatusand a replacement of worn parts is greatly facilitated.

The free end of shaft 34 is mounted in a rotatable manner in aconnecting yoke 46 by means of a roller bearing 45. Between the two endsof the connecting yoke 46, a slide ring 48 is rotatably mounted on ashaft 47. This slide ring 48 is positioned in a longitudinal groove 49of an adjusting lever 50 which is mounted on a support 52 so as to pivotabout a shaft 51. A crankarm 53 is hinged to the lower end of lever 50via a link pin 54, with the other end of crankarm 53 being hingedeccentrically to a crank disk 56 by means of a pin 55. Crank disk 56 ismounted on a gear 57 and is driven by a motor 58 mounted on a baseplate59 on frame 1.

it will thus be seen that the lateral displacement of the distributingrollers 18 and 19 depends on the distance of pin 55 from the center ofcrank disk 56 and the ratio of the length of the two portions of lever50 located above and below pivot point 51. This lateral displacementrange generally need not exceed 100 mm. and ranges preferably between 50and 100 mm., regardless of the width of the operative portion of theapparatus.

Two spray devices 60 and 61 are directed against distributing roller 19,which is the first roller encountered in the processing. These sprayingdevices 60 and 61 spray the developer on the upper surface of conveyorbelt 13 and the distributing roller 19, and thus to the upper surface ofthe printing plates (not shown) as indicated by dashed lines 62. Thesespray devices consist preferably of hollow rods with spray nozzles 63arranged and uniformly spaced on the bottom side of these rods.

As shown in FIG. 1, spray device 60 applies the developer directly tothe felt coat 22 of distributing roller 19, while spray device 61 spraysthe developer both against distributing roller 19 and also directly uponconveyor belt 13 and the printing plates placed thereon. Sincedistributing roller l9 rotates in a direction opposite to that in whichthe conveyor belt 13 moves, a wedge-shaped accumulation 64 of developerforms in front of the distributing roller 19 so that the printing platesare thoroughly immersed in developer. The developing by means of thepresent invention is thus carried out as uniformly as by hand, i.e., nounequally developed spots or stripes appear on the finished printingplates.

I claim:

1. Apparatus for providing a uniform coat of developer on printingplates, comprising a developing tank containing developer, a conveyorbelt adapted to carry the printing plates to be processed, at least twolongitudinally spaced rollers mounted above and relatively adjacent saidconveyor belt, means adjacent at least one of said rollers fordistributing the developer on said printing plates, means for rotatingsaid rollers in a direction opposite to the direction of travel of saidconveyor belt, and means for moving said rollers axially in a directiontransverse to said conveyor belt to provide a uniform coat of developeron the printing plates.

2. The apparatus of claim 1, further including a washing tank mountedadjacent said developing tank, said washing tank having mounted thereina plurality of vertically spaced conveying rollers adapted to engagesaid plates.

3. The apparatus of claim 2, wherein said washing tank is provided witha spray device for rinsing the plates with the washin liquid.

4. T e apparatus of claim 2, further including a common drive mechanismfor all of said rollers.

5. The apparatus of claim 1, further including at least one spray devicefor spraying the developer directly against the first of saiddistributing rollers, as seen in the direction of the processingsequence.

6. The apparatus of claim 5 wherein said one spraying device is directedagainst the top of said first distributing roller, and further includinga second spray device for spraying developer perpendicularly against thesurface of the said first distributing roller.

7. The apparatus of claim 1 wherein said distributing rollers areprovided with a coat of absorbent material.

8. The apparatus of claim 1 wherein said conveyor belt comprises anendless belt the lower section of which passes through the developerbath.

9. The apparatus of claim 8 further including circulating pump means forpumping developer from said bath to spray devices positioned above atleast one of said distributing rollers.

10. The apparatus of claim 1 wherein said distributing rollers are movedaxially back and forth by means of a lever operatively connected to amotor.

11. The apparatus of claim 10 wherein said distributing rollers aremounted on shafts axially slidable in bearing bushings, one end of eachof said shafts being engaged by said lever.

12. The apparatus of claim 11 wherein at least one bearing bushing ofeach distributing roller is rotatably connected with a drive mechanismand the distributing roller is carried along by this bearing bushing bya carrier.

13. The apparatus of claim 11 wherein said bearing bushings are eachpositioned in a support block, and means for vertically adjusting eachof said support blocks from the outside of the frame of the apparatus.

14. The apparatus of claim 1 wherein the range of axial movement of saiddistributing rollers is 50 to mm.

1. Apparatus for providing a uniform coat of developer on printingplates, comprising a developing tank containing developer, a conveyorbelt adapted to carry the printing plates to be processed, at least twolongitudinally spaced rollers mounted above and relatively adjacent saidconveyor belt, means adjacent at least one of said rollers fordistributing the developer on said printing plates, means for rotatingsaid rollers in a direction opposite to the direction of travel of saidconveyor belt, and means for moving said rollers axially in a directiontransverse to said conveyor belt to provide a uniform coat of developeron the printing plates.
 2. The apparatus of claim 1, further including awashing tank mounted adjacent said developing tank, said washing tankhaving mounted therein a plurality of vertically spaced conveyingrollers adapted to engage said plates.
 3. The apparatus of claim 2,wherein said washing tank is provided with a spray device for rinsingthe plates with the washing liquid.
 4. The apparatus of claim 2, furtherincluding a common drive mechanism for all of said rollers.
 5. Theapparatus of claim 1, further including at least one spray device forspraying the developer directly against the first of said distributingrollers, as seen in the direction of the processing sequence.
 6. Theapparatus of claim 5 wherein said one spraying device is directedagainst the top of said first distributing roller, and further includinga second spray device for spraying developer perpendicularly against thesurface of the said first distributing roller.
 7. The apparatus of claim1 wherein said distributing rollers are provided with a coat ofabsorbent material.
 8. The apparatus of claim 1 wherein said conveyorbelt comprises an endless belt the lower section of which passes throughthe developer bath.
 9. The apparatus of claim 8 further includingcirculating pump means for pumping developer from said bath to spraydevices positioned above at least one of said distributing rollers. 10.The apparatus of claim 1 wherein said distributing rollers are movedaxially back and forth by means of a lever operatively connected to amotor.
 11. The apparatus of claim 10 wherein said distributing rollersare mounted on shafts axially slidable in bearing bushings, one end ofeach of said shafts being engaged by said lever.
 12. The apparatus ofclaim 11 wherein at least one bearing bushing of each distributingroller is rotatably connected with a drive mechanism and thedistributing roller is carried along by this bearing bushing by acarrier.
 13. The apparatus of claim 11 wherein said bearing bushings areeach positioned in a support block, and means for vertically adjustingeach of said support blocks from the outside of the frame of theapparatus.
 14. The apparatus of claim 1 wherein the range of axialmovement of said distributing rollers is 50 to 100 mm.